intro story D-Flow FM


D-Flow Flexible Mesh

D-Flow Flexible Mesh (D-Flow FM) is the new software engine for hydrodynamical simulations on unstructured grids in 1D-2D-3D. Together with the familiar curvilinear meshes from Delft3D 4, the unstructured grid can consist of triangles, pentagons (etc.) and 1D channel networks, all in one single mesh. It combines proven technology from the hydrodynamic engines of Delft3D 4 and SOBEK 2 and adds flexible administration, resulting in:

  • Easier 1D-2D-3D model coupling, intuitive setup of boundary conditions and meteorological forcings (amongst others).
  • More flexible 2D gridding in delta regions, river junctions, harbours, intertidal flats and more.
  • High performance by smart use of multicore architectures, and grid computing clusters.
An overview of the current developments can be found here.
The D-Flow FM - team would be delighted if you would participate in discussions on the generation of meshes, the specification of boundary conditions, the running of computations, and all kinds of other relevant topics. Feel free to share your smart questions and/or brilliant solutions! 


We have launched a new website (still under construction so expect continuous improvements) and a new forum dedicated to Delft3D Flexible Mesh.

Please follow this link to the new forum: 

Post your questions, issues, suggestions, difficulties related to our Delft3D Flexible Mesh Suite on the new forum.





Sub groups
D-Flow Flexible Mesh
Cohesive sediments & muddy systems


Message Boards

Quicken Combine Depth and Uniform Value Polygons

Drew Mahedy, modified 7 Years ago.

Quicken Combine Depth and Uniform Value Polygons

I'm currently trying to generate individual .rgh roughness files via Quicken for multiple sub-domains in our estuary model. Each sub-domain is divided into regions of approximately equal roughness values. Therefore, the floodplain, river channel, and coastal nearshore regions each have a single .pol file with multiple polygons defined within each file (roughness areas are often not contiguous).

When I open one of this .pol files (floodplain for example) along with the respective sub-domain grid and depth file, I'm unable to change the depths within all the polygons using the Operations --> Combine Depth and Uniform Value --> Change Depth to Max of Depth or Uniform Depth operation. In other words, only depths within one of the polygons changes. Depths in the other polygons remain the same. Are you only allowed to save one polygon per .poly file for use in operations?

My system is large enough that having to generate, save, and then open .pol files for every contiguous area of the map rather than .pol files based solely on roughness type would be an enormous hassle and very time consuming.

FYI, I'm using Delft3D Quicken version 4.17.06

Jack Shipton, modified 7 Years ago.

RE: Quicken Combine Depth and Uniform Value Polygons

Hi Drew,

A method that has worked for me in the past is to use the ‘internal diffusion’ tool.
If you have multiple polygons you can seed an individual polygon with a single depth value using the edit depth function. You can then use the tool to fill whole polygons with single values. It sounds like your case is quite complex, so I’m not sure how applicable this suggestion is, I would suggest doing a test case to explore the limits of this tool.

Personally, I prefer keeping rgh files simple as they are often a key calibration parameter. Alternatively you could base your rgh file on your bathymetry (.dep file), using Excel or Matlab to convert depth ranges into a defined roughness value.